Method of constructing roadways



May 22, 1928. 1,670,346

s. E. FINLEY METHOD OF CONSTRUCTIXiG ROADWAYS Filed Nov. 29, 1926 Patented May 22, 1928.

UNITED STATES SAM EVERETT IINIJEY, OF ATLANTA, GEORGIA.

METHOD OF CONSTRUCTING ROADWAYS.

Application filed November 29, 1926. Serial No. 151,542.

The invention relates to a novel method of constructingroadways and more especially .to the reconstruction of existing roadways of the water-bound type, such as clay gravel, sand clay, top soil, water-bound macadam and the like to adapt the same to modern heavy automobile traffic, the object of the invention being to produce a roadway with a bitumen-bound wearing surface of .such stability that it will withstand the heavy impact of tratlic and the varying weather conditions, without impairment, and will be immune to the disintegration or ravelling effects along its marginal edges, as will be more particularly set forth in the annexed specification, predicated on the accompanying drawings, in which Fig. 1 is a sectional elevation of an ordinary water-bound roadway.

Fig. 2 is a similar view of the roadway, after the preliminary step of the method has been applied thereto.

, Fig. 3 is a similar view, illustrating the next or succeeding condition of the roadway.

Fig. 4 is a corresponding view showing the preferred mode of applying the bituminous binding inedium.

Fig. 5 is a sectional elevation of the completed roadway.

There are many miles of existing roadways and streets that were originally constructed for horse drawn trafiic, the body of the road structure consisting of clay gravel, top soil, sand or various admixtures ofthese elements bound with water, or straight water-bound macadam, and it was the common practice to construct these roads with a high crown, so that the water would drain freely from the surface of the roadway. Such road surfaces are wholly unsuited for present day trafiic, because they lack stability and are scoured off and rapidly disintegrated by the action of. the modern automobile tratlic. Furthermore, these high crowned roads are wholly unsuited for automobile traffic, because of the tendency of the vehicles to skid on such surfaces, unless the vehicle wheels actually span the high portion of the road crown. As a consequence, the traflic on such roads is concentrated in the middle of the roadway, which provides the only lane for safe travel. This causes a rapid deterioration of the travelled portion of the road, as the sides and edges are traversed only when IS vehicles pass one another. The portions of such a roadway when occupied by passing of water.

vehicles, to wit, the sides and edges, are also sub ect to impairment and general disintegration due to the side thrust imposed by the vehicles travelling on the lateral inclines of the crown, the result being severe rutting and scarring of the road surface and the ravelling of the marginal edges. Furthermore, the action of water running off the road or along the edges thereof produces an erosive effect, which rapidly destroys the edges and frequentlyworks back into the body of the road structure. As indicated, the invention is designed to obviate these objections, difiiculties and limitations inherent in these old types of roadways and streets, and to convert them into bituminous surfaced roadways with relatively flat crowns and marginal edges of reinforced bituminous concrete, so that the entire road structure will be safe for any type of vehicular tratiic and will resist the attritive forces of such traffic and of the elements,

not only with respect to the portion of the road surface subjected to heaviest traffic, but also along the lateral marginal edges, which are reinforced to prevent ravelling and eroslon.

Referring to the drawings, Fig. 1 illustrates, in cross section. a typical roadway constructed for vehicular traffic and comprises a body portion 1 of clay gravel. sand clay, top soil, or admixtures of these elements bound by water, or water-bound macadam, the road being provided with a relatively high crown, as indicated at 2, for the purpose of rapidly draining the roadway As indicated, roads of this type are wholly unsuited. to motor vehicular traf tic, first. because the road structure will not stand up under such trafiic, and second, he-

cause of the danger of the vehicles sliding or skidding off the road, when operating on the lateral portions thereof, as in passing other vehicles or obstructions'on the road. In carrying out the method which constitutes the present invention. the crowned surface of the road is 'scarified, and, if necessary.-compacted by means of a heavy roller. Along the marginal edges of the road a're excavated shallow trenches 3. which graduah ly decrease in depth toward the middle of the road. and which are preferably extended a short distance laterally of the road proper, when the road is bounded by side banks. Preferably, the material excavated from the trenches 3 is pulled or thrown back onto the road surface to materially reduce the pitch or crown of the road. although, in certain cases, this excavated material may be discarded. Along each marginal edge of the road are staked. or otherwise secured, edge defining forms 5. which are preferably timbers or strips of board or metal, to define the marginal edges of shoulders, which ar constructed by filling the shallow trenches with properly sized mineral aggregate 4. The body of mineral aggregate or broken stone 4 in each of the trenches may be of varying depths and thickness. depending upon the traflic the roadway or street is intended to carry. but. in every instance. it is thickest or deepest at the marginal edge and tapers ofi' toward the middle of the roadway. gradually merging into the contour of the surface. which is crowned or inclined laterally only sufiiciently to effectively carry off water falling thereon. These aggregate shoulders may be compacted and brought to contour with the road surface by rolling, either before or after the application of the bituminous binding medium. and. if necessary, the rolling may be applied to the entire road surface to reduce the same to the desired contour and grade.

After these operations have been completed, the forms 5 along one edge of the roadway are removed and a coating of bitu' minous binding material applied to the entire road surface, preferably by the mode disclosed in my prior Patent No. 1.544.440, with this modification. namely. that the amount of binding medium applied to the mineral aggregate 4. constituting the shoulders. is regulated in exact proportion to the depth or thickness of the body of aggregate, a maximum amount of binding medium being applied to the lateral faces of the mineral aggregate shoulder and gradually decreasing amounts of binding medium being applied to the surface of the shoulder by means of graduated spray nozzles on the distributor arm of the tank wagon. The spray nozzles, which apply the binding medium to the surface of the road between shoulders 4. are regulated to effect a substantially equal distribution of the binding medium over and into this surface to effect a uniform penetration and binding of the material of the road bed. so that. when the surface of the road is finished with a top dressing of fine stone chips. pea gravel, or similar aggregate. it constitutes a durable wear resisting and weather impervious support for all kinds and condition of trafiic, the specific characteristics of the road being illustrated in Fig. 5, in which 2' is the slightly crowned road surface coated and impregnated with sufficient bituminous binding medium to withstand the effects of all kinds of traffic and to resist the attacks of the elements, which is flanked by homogeneous mineral aggrcgate bituminous cement shoulders 4' which are strong enough to prevent ravelling and scouring even when the vehicle wheels pass over the edges thereof.

As a practical example of the application of the method, if the original roadway has a width of 18 feet. the headers 4', on either side thereof, would be approximately 4 feet in width. with a maximum thickness of 3 inches at their outer edges, which thickness diminishes toward the middle of the roadway until the surface of the header merges into that of the completed road. the mineral aggregate of the headers being bound by a bituminous medium applied thereto proportionately to the varying depth or thicknc.-; of the headers and the remainder of the road surface being coated with a uniform application of the binding medium. so that neither an excess nor a deficiency of binding medium prevails at any point.

Instead of coating the entire road surface with bituminous binding medium. it is obvious that the headers alone may be treated with the aforesaid proportionate distribution of bituminous binding medium and the main portion of the roadway between the headers may be finished with any suitable binder that will produce a wearing surface of appropriate stability and durability.

What I claim is:

1. The method of constructing roadways, which comprises preparing and forming the road surface to appropriate contour, excavating shallow shoulder defining trenches along the sides and decreasing in de th toward' the middle of the roadway, filling the trenches with mineral aggregate, forming the surfaces of the filling to the general contour of the road, applying a binding medium to the entire surface. and varying the amount of medium applied to the shoulders proportionately to the varying depths of the shoulders.

2. The method of constructing roadways, which comprises scarifying the surface, excavating shallow shoulder defining trenches along the sides and decreasing in depth toward the middle of the roadway, filling the trenches with mineral aggregate, forming the surfaces of the filling to the general contour of the road. applying a binding medium to the entire surface. and varying the amount of medium applied to the shoulders proportionately to the varying depths of the shoulders.

3. The method of constructing roadways, which comprises scarifying the surface, excavating shallow shoulder defining trenches along the sides and decreasing in depth toward the middle of the roadway, distributing the excavated material on the road surface, filling the trenches with mineral ag gregate, forming the surfaces of the filling to the general contour of the road, applying a binding medium to the entire surface, and varying the amount of medium applied to the shoulders proportionately to-the varying depths of the shoulders.

4. The method of constructing roadways, which comprises scarifying the surface, excavating shallow shoulder defining trenches along the sides and decreasing in depth toward the middle of the roadway, distribut ing the excavated material on the road surface, filling the trenches with mineral aggregate, forming and compacting the entire surface of the road to the desired contour, applying a binding medium to the entire surface, and varying the amount of medium edge defining forms along the outer margins of said trenches, filling the trenches with mineral aggregate, forming and compacting the entire surface of theroad to proper contour, applying a binding medium to the entire surface, and varying the amount of medium applied to the shoulders proportionately to the varying depths of the shoulders.

6. The method of constructing roadways, which comprises excavating shoulder defining trenches along the marginal edges of the road, which trenches decrease in depth toward the middle of the road, filling the trenches with a mineral aggregate, forming the surface of the filling to the general c0ntour of the road, and applying a bituminous binding medium to the aggregate shoulders varying in amount proportionately to the depth of the shoulders.

In testimony whereof I afiix my signature.

SAM EVERETT FINLEY. 

